• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.501-507
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• 2004

The uniquely large dimensions of Giant radio galaxies (GRGs) make it possible to probe for stringent limits on total energy content, Faraday rotation, Alfven speeds, particle transport and radiation loss times. All of these quantities are more stringently limited or specified for GRG's than in more 'normal' FRII radio sources. I discuss how both global and detailed analyses of GRG's lead to constraints on the CR electron acceleration mechanisms in GRG's and by extension in all FRII radio sources. The properties of GRG's appear to rule out large scale Fermi-type shock acceleration. The plasma parameters in these systems set up conditions that are favorable for magnetic reconnection, or some other very efficient process of conversion of magnetic to particle energy. We conclude that whatever mechanism operates in GRG's is probably the primary extragalactic CR acceleration mechanism in the Universe.

• Journal of The Korean Astronomical Society
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• v.34 no.3
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• pp.129-135
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• 2001

We report results from an analysis of the X-ray archival data on MCG-2-58-22 obtained with Ginga, ROSAT and ASCA. By analyzing both short- and long-term light curves, we find clear time variations, ranging widely from, $\~10^3$ s to more than several years, in the X-ray energy range 0.1 - 10 keV. In addition, a flare is detected in 1991, overlaid on a gradual, secular flux decrease from 1979 to 1993; this flare has a time scale of about 1 year, and the X-ray flux increased by at least a factor of 3. The implications of these observational results are discussed in terms of accretion flow dynamics near a supermassive black hole.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.393-394
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• 2004

To get rid of cell assembly margin and have more process room of upper substrate, we developed truly COT (Color Filter On TFF Array) LCDs in that B/M (Black Matrix) as well as C/F (Color Filter) layer is located on TFT substrate. Novel B/M material is also developed for this COT structure. Difficulty in making contact hole through C/F layer was solved by making each C/F pattern isolated from others. We think this configuration will be core technology for prominent COT LCDs.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.2
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• pp.75-82
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• 2014

MANET has various types of attacks. In particular, routing attacks using characteristics of movement of nodes and wireless communication is the most threatening because all nodes which configure network perform a function of router which forwards packets. Therefore, mechanisms that detect routing attacks and defense must be applied. In this paper, we proposed hierarchical structure attack detection techniques in order to improve the detection ability against routing attacks. Black hole detection is performed using PIT for monitoring about control packets within cluster and packet information management on the cluster head. Flooding attack prevention is performed using cooperation-based distributed detection technique by member nodes. For this, member node uses NTT for information management of neighbor nodes and threshold whether attack or not receives from cluster head. The performance of attack detection could be further improved by calculating at regular intervals threshold considering the total traffic within cluster in the cluster head.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.22.2-22.2
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• 2008

Radio and X-ray observations of radio lobes in galaxy clusters indicate large energies stored in the magnetic fields in the radio lobes. These magnetic fields are undoubtedly produced and amplified by the accretion onto the central supermassive black hole. I review recent progress and remaining problems in our understanding of the ways how these magnetic fields can be produced and amplified in the accretion disks and what can be the limiting strength of the magnetic field. The major remaining issue is how ordered magnetic spirals (or jets) can emerge from the turbulent small scale magnetic fields produced by MRI. Another issue is the ratio of the axial to the azimuthal magnetic field in jets.

• Proceedings of the Korea Contents Association Conference
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• 2003.05a
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• pp.470-473
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• 2003

We have the index form of the multiply warped products manifold. From this result we will investigate the physical properties on the Robertson-Walker spacetime. The singularly thorem are usually interpreted as an indication that black hole exist and that there has been a big bang. This paper include necessary condition for the Robertson-Walker spacetime with singularly.

• Journal of the Korean institute of surface engineering
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• v.34 no.3
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• pp.187-194
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• 2001

Galvalume sheet steel was developed recently, and is used widely in several fields. It has and had a good corrosion resistance in open atmosphere, but it has week corrosion resistance in the ambient surroundings of an airtight packing. Therefore, black patina was synthesized on the surface of Galvalume sheet steel. Corrosion by moisture on a Galvalume surface begins from edge of a droplet and proceeds to the center of droplet. It begins mainly on the interdendritic structure instead of dendritic structure. This suggests that corrosion by moisture occurs on the Zn shrinkage hole from rapid air cooling. In addition, the initial corrosion occurs by the local cell and continues by the oxygen concentration cell.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.59.1-59.1
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• 2014

AGN feedback has been believed as playing an important role in the galaxy-super massive black hole (SMBH) co-evolution. AGN gas outflow can lead to AGN feedback. We investigate gas outflow of low-redshift AGNs by using blue shift/asymmetric index (BAI), and velocity offset of CIV line. By comparing these gas outflow indicators (BAI and velocity offset) to AGN properties (i.e., SMBH mass, bolometric luminosity, and Eddington ratio) and BLR gas metallicity, we find positive correlations among outflow, Eddington ratio, and metallicity. These relations are consistent with those observed at high-redshift. We discuss the possibility of the connection between previous star formation with current AGN accretion and outflow.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.50.1-50.1
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• 2012

As a tracer of star formation history, metallicity provides crucial information for understanding galaxy evolution. In the case AGN, gas metallicity is often derived from the flux ratio of UV emission lines, i.e., NV1240 and CIV1549. To investigate the dependence of metallicity on AGN luminosity, black hole mass, and accretion rate, we measure NV1240 and CIV1549 line fluxes and derive gas metallicity of a sample of 73 local Seyfert 1 galaxies and QSOs, using archival UV spectra obtained with the HST and IUE. In this work, we will present the metallicity of local AGN and its relation with AGN properties.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.35.1-35.1
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• 2012

Determining the virial factor of the broad-line region (BLR) gas is crucial in calibrating AGN black hole mass estimators, since the measured line-of-sight velocity needs to be converted into the representative velocity of the BLR gas. The unknown virial factor has been empirically calibrated based on the $M_{BH}-{\sigma}_*$ relation of non-AGN galaxies, but the claimed values are different by a factor of 2 in recent studies. We investigate the origin of the difference by measuring the $M_{BH}-{\sigma}_*$ relation using the most updated nearby galaxy sample, and explore the dependence of the virial factor on the various fitting methods. We find that the discrepancy is mostly caused by the sample bias while the difference stemming from various regression methods is marginal. Based on the best-determined virial factor, we present the updated $M_{BH}-{\sigma}_*$ relation of local active galaxies.